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Thursday, January 24, 2008

Fiat Bravo: In Depth

Cruise Control

The Cruise Control system available on the Fiat Bravo helps the motorist to control the vehicle speed, enhancing travelling comfort. The device acts directly on the engine throttle, automatically maintaining the cruising speed set by the driver. It is only necessary to turn the ring on the special lever positioned to the left of the steering wheel to the 'ON' position, adjusting the speed using 'plus' (or 'minus'). When the ring is released the car will continue to travel at the memorised speed without the driver having to touch the accelerator pedal.

Cruise Control can function over the engine entire rpm range, but only at speeds above 40 km/h. So it is advisable to activate it in road conditions that will make it possible to maintain the memorised value safely.

If the accelerator pedal is pressed (for example to overtake), Cruise Control is momentarily over-ridden, but the system remains active. The car will therefore accelerate as requested, but as soon as the pedal is released, the system will resume the memorised speed. For obvious safety reasons, the device is automatically de-activated if the driver puts his foot on the brake or clutch pedal. In this case, the 'RESUME' button on the end of the Cruise Control system control lever must be pressed to recover the pre-set speed.

To definitively de-activate Cruise Control and cancel any previous setting, the ring nut must be turned to the 'OFF' position and the engine turned off. A telltale on the multifunction display indicates whether the system is operating or de-activated. The ASR system (Anti Slip Regulation) takes priority over the automatic speed control; if ASR has to intervene, the system will then resume the set speed.

Parking sensor

During parking manoeuvres, obstacles behind the car may be outside the driver field of vision, or he may simply not know how much space separates his car from the car parked behind. In this situation the parking sensor can help; it is activated every time reverse is engaged when the ignition key is in the MAR position.

The system comprises an electronic control unit with an interface for the CAN network, four ultrasonic sensors in the rear bumper and a beeper. The four sensors cover both the rear side areas of the car (from a distance of less than 60 centimetres), and central rear area (from a distance of less than 150 cm).

We can see how it functions in detail. The four ultrasonic transducers act as intelligent transmitters and receivers of impulses. The latter are emitted every time reverse is engaged; if they meet an obstacle they are reflected and received like an echo by the sensor itself. At this point the incoming signal is converted into a digital signal and sent to the electronic control unit, which activates the acoustic alarm. The information is then transmitted to the driver by intermittent beeps, which become more insistent until the car reaches a distance of 30 centimetres from the obstacle, when the signal becomes constant.

The beeping stops if the lateral sensors detect an approaching obstacle for more than three seconds, so that the system does not continue to beep while parking along a wall parallel to the vehicle axis. The parking system is also available with eight sensors (the additional four sensors cover the front end of the Bravo).

Rain sensor

Good visibility at all times is an important aspect of preventive safety. Which is why the Fiat Bravo offers a rain sensor, to ensure that the windscreen is always clean, even in bad weather. The system is applied in the upper part of the passenger compartment, behind the central rearview mirror, and it automatically activates the windscreen wipers and regulates their frequency depending on the intensity of the rain. It is activated by moving the right-hand steering wheel stalk to the first position (intermittency), and its operation is based on the principle of the refraction of infrared rays through the glass and the drops of water. The optical element of the sensor (lens) sends an infrared ray to the windscreen, which reflects it and sends it back to the sensor. Because the luminous energy sent to the windscreen is constant, the value measured on the light received decreases as the quantity of water and other impurities on the windscreen increases. The variation in the signal is processed by the electronic element of the sensor, which activates the appropriate wiper stroke frequency.

Since the wet surface disturbs the human eye more at night than during the day, the sensor also regulates the wiper strokes on the basis of ambient light. And it recognises water streaks caused by worn blades, compensating for the effects of the ageing of the windscreen and electronics. And in particular situations, it activates special stroke cycles: for example, when there are only a few drops of rain, or impurities (saline deposits, dirt, etc.), on the windscreen surface.

The sensitivity of the rain sensor can be modified by adjusting the two-position ring nut on the right steering wheel stalk. If the engine is stopped with the system engaged, this is automatically de-activated. When the engine starts again, the system can be re-activated by moving the stalk to zero and then back to the first position, or by adjusting the sensitivity of the sensor.

To indicate that it has been re-activated, the system will perform one stroke of the wipers, even if the windscreen is dry. After the windscreen washer pump has been used, the sensor is activated automatically for the time necessary to catch the drops dripping down the glass.

Tyre pressure sensor

The new Fiat model also includes a tyre pressure sensor, a device that indicates any anomalies with both an acoustic alarm and an icon on the display. The TPMS (Tyre Pressure Monitoring System) monitors two conditions: insufficient pressure and a puncture. If one of these two thresholds is passed, the telltale will light up and a message will appear on the display. And in the case of a puncture, the instrument panel will also emit an acoustic signal.

'Small' devices for outstanding comfort

The Fiat Bravo changes the quality of the way we live and travel in a car. Thanks, for example, to the 'follow me home' system that keeps the headlights on for a moment when you get out of the car, or the new FIX&GO system to repair punctured tyres, or tinted windows for greater privacy. The customer can also choose electric rear windows with an anti-pinch device built into the upper seal of the windows. This device detects the presence of an obstacle between the seal and the upper edge of the glass and immediately inverts the direction of the window mechanism.

One of the most interesting features proposed on the new model is the dead-lock, a technical solution that puts the inside door handle and all the levers connected with the lock, into neutral. This is an important step forward that protects the car against theft: the dead-lock renders ineffective any tool used by thieves to force the door or its internal mechanisms. The device must be activated deliberately (so that no one is locked in the car by mistake). After the first turn of the key in one of the front doors, or the first impulse of the remote control, a second turn, or a second impulse, is necessary to engage the dead-lock.

The Bravo also offers a cargo box which raises the loading floor, making it possible to store small personal items in the space below, and it also creates a single loading floor, level with the folded seat. And finally, the entire range is available with the Dualdrive power steering system which is fitted with two functioning logics and uses the power generated by a small electric motor instead of that supplied by a hydraulic pump driven directly by the engine. What is more, with the electric power steering system, the steering response is correlated to the speed of the car: the higher this is, the lower the level of servo assist and the more effort required to steer, which guarantees more precise steering. That is not all. This innovative electrical power steering device offers customers another opportunity: that of choosing between two different calibration programs. The first, which enhances the understanding between the driver and the car, is ideal on mixed out-of-town routes. The second, which lightens the steering and therefore requires less effort, is perfect in town and for parking manoeuvres. The latter is engaged by pressing the 'city' key at the centre of the facia. But if a driver takes to the motorway and forgets to de-activate the device, it is not a problem. To guarantee maximum safety at all times, above 30 km/h the two systems provide the same amount of servo assist, thus ensuring that the steering wheel responds correctly even at high speeds.